All references cited herein, as well as the priority document German Patent Application 19728108.7 filed Jul. 2, 1997, are incorporated herein by reference in their entirety and for all purposes to the same extent as if each individual publication or patent or patent application was specifically and individually indicated to be incorporated by reference in its entirety for all purposes.
1. Field of the Invention
The invention relates to an X-ray examination apparatus which includes a patient table which is tiltable about a horizontal axis, an image converter arrangement which is displaceable in the longitudinal direction of the table, and an overtable X-ray source which is aligned with respect thereto.
2. Description of Related Art
X-ray examination apparatus of this kind are known in practice, for example the Philips apparatus xe2x80x9cDIAGNOST 120xe2x80x9d. The X-ray source and the image converter arrangement thereof are accommodated on a carriage which is displaceable in the longitudinal direction of the table. Such an X-ray examination apparatus has a comparatively complex construction and it is suitable for different examination methods to a limited extent only.
Therefore, it is an object of the present invention to construct an X-ray examination apparatus of the kind set forth in such a manner that a simple construction is obtained which nevertheless enables more universal application.
This object is achieved according to the invention in that the X-ray source is mounted on a horizontally displaceable stand so as to be displaceable in the vertical direction and can be coupled, via a mechanical coupling member, to the patient table in such a manner that upon tilting of the patient table the stand and the X-ray source are displaced in such a manner that the distance between and the alignment of the image converter arrangement and the X-ray source with respect to one another remain the same.
Thus, the X-ray examination apparatus according to the invention includes, in addition to the patient table with the image converter arrangement, which is displaceable in the longitudinal direction of the table, a stand which is slidable in the horizontal direction and on which the X-ray source is mounted so as to be slidable in the vertical direction. The coupling member enables the patient table and the X-ray source to be coupled to one another in such a manner that in response to a tilting motion of the patient table the stand is displaced in the horizontal direction and the X-ray source is displaced in the vertical direction, the distance between and the alignment of the image converter and the X-ray source with respect to one another remaining the same. All customary fluoroscopy methods can be executed by means of such an X-ray apparatus. Moreover, the X-ray examination apparatus according to the invention is also suitable for executing Bucky exposures with a vertical beam path. The displaceability of the stand enables the use of a patient table which is not provided with a xe2x80x9cfloatingxe2x80x9d table top but with a table top which is fixed relative to the table frame, resulting in a substantially simpler construction.
When the coupling member is decoupled from the X-ray source, further possibilities arise. In an embodiment, X-ray exposures can be performed by means of the X-ray source on a separate image pick-up device, for example mounted on a Bucky wall stand; the beam path may then extend horizontally and parallel to the direction of displacement of the stand. Another embodiment enables adaptation to different patient sizes. A further embodiment enables X-ray exposures with a beam path extending horizontally and perpendicularly to the longitudinal direction of the table.
Another embodiment offers the above-mentioned examination possibilities in the first mode of operation (rigid coupling between X-ray source and image converter); linear tomography or oblique exposures are possible in the second mode of operation.
The first and the second mode of operation can be implemented by means of the following embodiments. When the carriage supporting the unit for adjusting the slice height is displaced (first mode of operation), the described X-ray fluoroscopy or Bucky exposures are possible. However, when the carriage is blocked relative to the patient table, the X-ray source and the image converter arrangement are displaced in opposite directions. This enables, for example oblique exposures. A preferred embodiment of the invention enables the position of the examination zone to be changed in the first mode of operation and linear tomography to be performed in the second mode of operation.
Yet another embodiment takes into account the fact that the image converter arrangement usually utilizes separate image converters for X-ray fluoroscopy and X-ray exposures. It is thus possible in principle to use an additional carriage for the unit for slice height adjustment.
A preferred embodiment has a construction which is mechanically simpler and also more stable. A further embodiment enables very simple changing over between the two modes of operation. When the two carriages are displaced at the same speed (or when both carriages stand still), X-ray fluoroscopy or Bucky exposures are possible (first mode of operation). When the second drive device has been deactivated and the first drive device acts on the carriage coupled to the coupling member, linear tomography can be performed. A common drive motor can be used for the two drive devices, said motor acting, via a coupling that can be activated and deactivated, on a drive member in the form of, for example a drive spindle.